In some systems, a server collects information from apparatuses that are targets for information collection, and these apparatuses are managed using the pieces of the collected information. For example, in order to reduce a loss of sales opportunities, a management system collects inventory information from vending machines, and thus detects an out-of-stock condition in a vending machine, predicts a time when the vending machine becomes an out-of-stock condition, and so forth. Furthermore, for example, a management system for propane gas collects information relating to the amount of remaining gas from a gas cylinder of propane gas in order to efficiently perform a job of delivering the propane gas.
Patent Documents 1 to 4 are considered as examples of documents that disclose technologies relating to the information collection. Patent Document 1 discloses a technology for collecting sales information of vending machines through a personal handy-phone system (PHS) link. An apparatus that performs PHS communication is provided in each vending machine. Then, each vending machine performs the PHS communication and transmits information to the center.
Patent Document 2 discloses a technology for collecting maintenance information of an elevator using a wireless IC tag. Specifically, the elevator has a function of transmitting the maintenance information from the wireless IC tag, and the wireless IC tag is read using a dedicated portable terminal that includes a wireless IC tag reader. Thus, the maintenance information is collected from the elevator. Then, the information collected by the portable terminal is transferred to a portable terminal that is present in an office in which an operator works.
Patent Document 3 discloses a communication system that transmits information transmitted by a portable terminal with a low-level function, to a base station through a portable terminal with high-level function. The portable terminal with the high-level function has an authentication function in which control is performed in such a manner as to relay only information transmitted from the portable terminal with the low-level function that has a predetermined telephone number.
Patent Document 4 discloses a system that transmits data using multiple channels when data is transmitted from a base station to a terminal station. As one method, there is a method in which data is divided and pieces of data that are different from each other are transmitted using two channels. Furthermore, as another method, there is a method in which a base station transmits the same data using two channels.